1. Field of the Invention
The present invention relates to a steering apparatus of a small ship such as a motorboat, and more particularly, to a steering apparatus for eliminating a gap between a rotary cover and a rotary plate of the steering apparatus to prevent abrasion and noise from being generated caused by the gap to thereby maximize steering handle rotation prevention effect.
2. Background of the Related Art
Generally, a small ship includes a steering handle H which is rotatable and provided in front of a cabin and an engine E which is horizontally rotatable and attached to the stern, as illustrated in FIGS. 1 and 2.
The handle H is connected to the engine E via a steering module 100 and a cable C, and thus the cable C is pulled or released through the steering module 100 when a driver operates the handle H to rotate the engine E to the left or right so as to change the direction of the ship.
A handle steering apparatus includes a top case 200, a bottom case 300, the steering power transmission module 100, a steering shaft 400, a reduction gear unit 500 and a torque module 700.
The steering power transmission module 100 includes a rotating plate 110, which is set inside the top case 200 and the bottom case 300 and rotated by the rotary power of the steering handle H, and the cable C winding round the outer rim of the rotating plate 110.
The top case 200 has a penetration hole 210 formed at the center thereof, four insertion grooves 230 formed at the inner side thereof, and two cable guide grooves 250 through which the cable C connected to the rotating plate 110 passes. The two cable guide grooves 250 are formed at one side of the top case 200 and opened to the outside of the top case 200. The steering shaft 400 penetrates the penetration hole 210.
The bottom case 300 includes an internal gear 310 formed at the inner side thereof and a shaft hole 330 formed at the center thereof. The steering shaft 400 penetrates the shaft hole 330.
The reduction gear unit 500 is set in the bottom case 300 in contact with the internal gear 310. The reduction gear unit 500 includes a shaft gear 500 and three gears 510 for reducing the speed of revolution of the handle H and transmitting the reduced speed to the rotating plate 110. The three gears 510 are arranged around the shaft gear 500 and engaged with the shaft gear 500.
The steering shaft 400 includes a screw thread 410 formed at one end thereof, penetrates the top case 200 and the bottom case 300 and is combined with the handle H by using the screw thread 410. The other end of the steering shaft 400 is inserted into the shaft hole 330 of the bottom case 300.
The torque module 700, which controls the operating power of the steering shaft 400, is attached to the steering shaft 400 rotated by the operating power of the handle H. The torque module 700 is disclosed in Korean Patent No. 10-0748428 previously applied by the Applicant.
Specifically, the torque module 700 includes a cylindrical fixed frame 710 fixed to the top case 200, a rotary plate 720 rotatably set in the fixed frame 710, a plurality of mounts 721 which are arranged on the rotary plate 710 such that rolling elements 730 and elastic elements 740 are mounted thereon, and a rotary cover 760 which includes a movable part having movable pieces 761 capable of pressing the rolling elements 730 when the steering shaft 400 is operated and covers the top of the rotary plate 720 to prevent the rolling elements 730 and the elastic elements 749 from being separated from the torque module 700.
The steering shaft 400 penetrates the fixed frame 710, the rotary plate 720 and the rotary cover 760. The fixed frame 710 includes a plurality of protrusions 711 formed on the outer face thereof. The protrusions 711 of the fixed frame 7100 are inserted into the four insertion grooves 230 of the top case 200 to prevent the steering apparatus from rotating.
The movable pieces 761 of the rotary cover 760 are tapered in such a manner that the ends of the movable pieces 761 are thinner, and thus the rotary cover 760 can be easily removed from a mold when the rotary cover 760 is manufactured.
In the conventional steering apparatus described as above, when the handle H is rotated to one direction while the ship is running, the operating power of the steering shaft 400 is transmitted to the rotating plate 110 through the reduction gear unit 500 to rotate the rotating plate 110 to the left or right. The cable C is pulled or released according to the revolution of the rotating plate 110 to move the engine E to the left or right so as to adjust the moving direction of the ship.
The operation of adjusting the moving direction of the ship and a function of preventing the steering handle H from rotating when a driver does not grip the steering handle H will now be explained in detail with reference to FIGS. 3 through 8.
When the steering handle H is rotated to the left or right (clockwise or counter clockwise) according to the rotating power of the steering shaft 400 while the ship is running, the movable piece 761 presses the rolling elements 730 located in the rotating direction of the handle H, and thus the rolling elements 730 are separated from the inner face of the fixed frame 710 according to compression of the elastic elements 740 (refer to “A” of FIG. 5 and “B” of FIG. 7).
Rolling elements 730 which are not pressed by the movable piece 761 are movable although they are pressed against the inner face of the fixed frame 710 according to the restoring force of the elastic elements 740.
That is, when the handle H is rotated to the left or right (clockwise or counter clockwise) according to the operating power of the steering shaft 400, the rotary cover 760 is rotated and the rolling elements 730 located in the rotating direction are separated from the inner face of the fixed frame 710 according to compression of the elastic elements 740 to rotate the rotary plate 720. Accordingly, the operating power is transmitted to the cable C through the reduction gear unit 500 to adjust the direction of the ship.
When the operating power is eliminated, the rolling elements 730 mounted on the mounts 721 are pressed against the inner face of the fixed frame 710 and function as a wedge to fix the rotary plate 720, as illustrated in FIGS. 3 and 4, and thus the steering shaft 400 is fixed and the direction of the ship is also fixed.
However, the conventional steering apparatus has the following problem.
A gap t between the rotary plate 720 and the rotary cover 760 affects the operation of the handle H.
That is, when the cable C vibrates according to vibration of the engine E, the movable pieces 761 are affected by the cable C, and thus the handle H idles within the gap t between the movable pieces 761 and the rolling elements 730 to generate noise and abrasion at the movable pieces 761 and interfered portions of the movable pieces due to the gap t.
When the driver steers the steering handle H to the left or right, the steering handle H is moved to the left or right and the cable C is also moved to the left or right. Even when the engine E vibrates while the steering handle H is stopped by the operation of the steering apparatus to apply a force in the range of 700 to 800 kg to the cable C, the steering handle H is not moved.
As described above, the conventional steering apparatus generates noise and abrasion due to the gap between the rotary plate 720 and the rotary cover 760. The gap makes the steering handle H drag when the driver initially operates the steering handle H because the movable pieces 761 of the rotary cover 760, which are made of metal, and the rotary plate 720 come into contact with each other.
Furthermore, since the movable pieces 761 of the rotary plate 760, which press the rolling elements 730, are tapered in order to easily separate the rotary plate 760 from the mold when the rotary plate 760 is manufactured, the movable pieces 761 partially come into contact with the rolling elements 730 (refer to FIG. 6).
Accordingly, partial load is applied to the rolling elements 730, and thus reliability of the operation of the torque module 700 may be deteriorated and components being in contact with each other may be partially abraded.